Many oil and gas wells are prone to deposition of substances, such as mineral salts, usually referred to as scale, on the walls of the various tubular goods and components which are contacted by reservoir fluid. The scaling phenomenon is particularly prevalent for oilfields where pressure maintenance by water injection is practiced. Some of these salts, for example calcium carbonate, may be chemically removed by a relatively small amount of any acid, while others, like barium sulphate, may require copious supplies of a special organic acid to dissolve them. Modern well completion allows easy removal of calcium carbonate and similar scales in many cases, whereas barium sulphate removal usually entails pulling the tubular goods that can be pulled and/or milling out scale on permanently installed tubulars.